17 research outputs found
Customer segmentation in the medical devices industry
No full textThesis (M. Eng. in Logistics)--Massachusetts Institute of Technology, Engineering Systems Division, 2007.Includes bibliographical references (p. 73-76).This thesis addresses Company X's concerns about its product shipment options. The company ships over 70% of its products to its customers using the primary service provider that ensures that the product is at the customer site by 10:30 AM next day. As per the understanding with its customers, the company, absorbs the cost of premium shipping and does not pass it on to most of its customers. The company believes that this priority service is a source of competitive advantage that helps it get customer loyalty and thereby increases sales. However it is not a normal industry practice to provide this service free to the customers. Keeping in mind this enormous cost burden, Company X wants to minimize this cost. Medical device sales are non-seasonal and do not show promotional effects. We analyzed data for the months of June and October, 2006 as a part of our research. The objective of our data analysis was to validate the proposed approaches we reviewed as a basis for proposing ways to segment customers for improving service while reducing cost. We proposed three types of segmentation: by region, by order method and by division. Segmentation by region looks at dividing the customers by into 4 regions based on their location.(cont.) Segmentation by ordering method splits the customers in terms of whether they order using phone, fax or EDI while segmentation by division breaks up the customer base in terms of the various divisions the company has. Our study revealed that the company can expect to save over 3 million dollars annually by not offering this service free of charge to its customers. If customers are not convinced that the lower level of service meets their needs, they may pay for use of premium shipping. We demonstrate that the lower level of service will likely be just as effective and hence the company can guarantee that the product would reach the customer on time. Given the criticality of the parts that the company ships, it is advised to take its customers into confidence before making major policy changes.by Probal Basu [and] Eun Kyun Kim.M.Eng.in Logistic
Study on Calcium Reinforced Polymeric Hydrogel Scaffolds for Bone Tissue Regeneration
No full textLéčba nežádoucích zlomenin se potýká s celou řadou problémů jako jsou infekce či další následné vynucené chirurgické zákroky. Pro řešení těchto případů se s výhodou dají použít polymerní scaffoldy, které dokáží vylepšit regeneraci kostní tkáně. Polymerní scaffoldy mají totiž vynikající biokompatibilitu, vhodné mechanické vlastnosti a jsou dobře odbouratelné v tkáni. Tato práce se zabývá přípravou a charakterizací nových polymerních hydrogelových scaffoldů na bázi bakteriální celulózy (BC) plněné vápníkem, jejichž úkolem je zvýšit regeneraci poškozené kostní tkáně. Byly připraveny scaffoldové kompozice na bázi BC a syntetických polymerů polyvinylpyrrolidonu (PVP) a polyethynglykolu (PEG) ve dvou kombinacích. V prvním případě byly použity hydrogelové scaffoldy na bázi BC plněné/vyztužené fosfátem vápenatým (CaP), kde CaP byl ve formě beta-tri-fosfosfátu vápenatého ("beta"-TCP) a hydroxyapatitu (HA) v různých koncentracích. Druhou kombinaci tvořily hydrogelové scaffoldy na bázi BC plněné fosfátem vápenatým/uhličitanem vápenatým, které byly připraveny in vitro biomineralizací hydrogelového scaffoldu na bázi BC plněné CaP. Strukturální vlastnosti (fyzikálně-chemické, morfologické, mechanické a viskoelastické) naznačují, že scaffoldy plněné CaP mají značnou schopnost bobtnání, mají vhodnou pórovitost, a další mechanické a viskoelastické vlastnosti. Kromě toho výsledky testů funkčních vlastností, zahrnující biokompatibilitu, životaschopnost buněk, interakci buněk a biomateriálů (prostřednictvím studie SEM) a expresi kostních markerů (pomocí ALP analýzy) ukázaly lepší účinnost při regeneraci kostní tkáně. Na základě zjištěných poznatků lze hydrogelové scaffoldy na bázi BC vyztužené CaP (BC-PVP-"beta"-TCP / HA_20: 80 a BC-PVP-"beta"-TCP / HA_50: 50) doporučit k další analýze (např. Studiem in vivo) a případně použít navržený scaffold pro regeneraci měkkých (spongiózních) kostí.Treatments for unwanted bone fractures have different limitations like potential infection risks and requirement of secondary surgery. Polymeric tissue engineering scaffold material can be a suitable alternative treatment device for the bone tissue regeneration due to its excellent biocompatibility, mechanical property and degradability. This thesis reports the preparation and characterization of novel calcium reinforced bacterial cellulose (BC) based hydrogel scaffolds for its possible application in bone tissue regeneration. The scaffolds were developed by using a combination of natural polymer, BC and other synthetic polymers like polyvinylpyrrolidone (PVP), polyethylene glycol (PEG). The scaffolds were prepared in two forms. First, calcium phosphate (CaP) reinforced BC based hydrogel scaffolds were prepared, where CaP was used in the form of "beta"-tri calcium phosphate ("beta"-TCP) and hydroxyapatite (HA) in different concentrations. Second, calcium phosphate & calcium carbonate reinforced BC based hydrogel scaffolds were prepared through template mediated in vitro biomineralization of CaP filled BC based hydrogel scaffolds. The structural properties (physiochemical, morphological, mechanical and/or viscoelastic characterization) indicated the CaP reinforced scaffolds have demonstrated significant swelling ability, suitable porosity and other mechanical and viscoelastic properties. Furthermore, functional properties (involving the biocompatibility, cell viability, cell-biomaterial interaction and bone marker expression) indicated their better efficiency for bone tissue regeneration. Thus, the CaP reinforced BC based hydrogel scaffolds (BC-PVP-"beta"-TCP/HA_20:80 and BC-PVP-"beta"-TCP/HA_50:50) are recommended for further analysis (e.g. in vivo study) and application in soft bone tissue (ie. cancellous bone) regeneration.Centrum polymerních materiál
Ecology and Biology of Culex quinquefasciatus Say, 1823, in Two Physiographically Different Ecosystems with Special Reference to Human Lymphatic Filariasis in West Bengal, India
No full textRheological performance of bacterial cellulose based nonmineralized and mineralized hydrogel scaffolds
No full textBacterial cellulose (BC) based hydrogels (BC-PVP and BC-CMC) are modified with β-tri-calcium phosphate (β-TCP) and hydroxyapatite (HA) to improve the structural and functional properties of the existing hydrogel scaffolds. The modified hydrogels are then biomineralized with CaCO3 following liquid diffusion technique, where salt solutions of Na2CO3 (5.25 g/100 mL) and CaCl2 (7.35 g/100 mL) were involved. The BC-PVP and BC-CMC are being compared with the non-mineralized (BC-PVP-β-TCP/HA and BC-CMC-β-TCP/HA) and biomineralized (BC-PVP-β-TCP/HA-CaCO3 and BC-CMC-β-TCP/HA-CaCO3) hydrogels on the basis of their structural and rheological properties. The Fourier Transform Infrared (FTIR) spectral analysis demonstrated the presence of BC, CMC, PVP, β-TCP, HA in the non-mineralized and BC, CMC, PVP, β-TCP, HA and CaCO3 in the biomineralized samples. Interestingly, the morphological property of non-mineralized and biomineralized, hydrogels are different than that of BC-PVP and BC-CMC based novel biomaterials. The Scanning Electron Microscopic (SEM) images of the before mentioned samples reveal the denser structures than BC-PVP and BC-CMC, which exhibits the changes in their pore sizes. Concerning rheological analysis point of view, all the non-mineralized and biomineralized hydrogel scaffolds have shown significant elastic property. Additionally, the complex viscosity (η∗) values have also found in decreasing order with the increase of angular frequency (ω) 0.1 rad.sec-1 to 100 rad.sec-1. All these BC based hydrogel scaffolds are elastic in nature, can be recommended for their application as an implant for bone tissue engineering. © 2017 Author(s).Internal Grant Agency [IGA/CPS/2017/003]; Tomas Bata Univerity in Zlin, Czech Republic; Ministry of Education, Youth and Sports of the Czech Republic - NPU Program I [LO1504
Viscoelastic behavior of calcium phosphate packed bacterial cellulose -polyvinylpyrrolidone based hydrogel scaffolds at human fever temperature
No full textCalcium phosphate (CaP) packed bacterial cellulose (BC) and polyvinylpyrrolidone (PVP) based hydrogel scaffolds (BC-PVPCaP) are being reported here considering its possible application in bone restoration. The primary focus of this work is to analyze the viscoelastic behavior of 'BC-PVP-CaP' hydrogel scaffolds at human fever temperature condition (39°C) in swelled state. In BC-PVP scaffolds, CaP [in the form of β-tricalcium phosphate (β-TCP) and hydroxyapatite (HA) is present as filler in different concentrations (i.e. β-TCP/HA_20:80, β-TCP/HA_40:60, β-TCP/HA_50:50). The BC-PVP scaffold (without CaP) was marked as a control set for the evaluation of viscoelasticity of scaffolds. The BC-PVP-CaP_50:50 hydrogel scaffold showed the highest degree of swelling at 39°C among the other BC-PVP-CaP scaffolds. However, the other hydrogel scaffolds were also showed notable viscoelasticity at 39°C. Experimental results confirmed that the CaP filled BC-PVP hydrogel scaffolds (BC-PVP-CaP_20:80, BCPVP- CaP_40:60, BC-PVP-CaP_50:50) exhibit a promising viscoelastic behavior at human fever temperature condition (39°C), can be endorsed for its potential application in bone repairing /bone restoration. © 2020 American Institute of Physics Inc.. All rights reserved
Changing epidemiology of SARS-CoV in the context of COVID-19 pandemic
No full textSARS-CoV2 is a new form of β‐coronavirus that has been recently discovered and is responsible for COVID 19 pandemic. The earliest infection can be traced back to Wuhan, China. From there it has spread all over the world. It is considered to have a zoonotic origin in bats and has resulted in human to human transmission. SARS-CoV2 is considered to be a strain of SARS-CoV that has a high rate of pathogenicity and transmissibility. It has been documented that the total number of confirmed cases and deaths in Europe is comparatively significant than other parts of the world. Thus, keeping in view the above perspective, an attempt is made in order to find out the epidemiological pattern of COVID 19 pandemic, if any, in different geo-climatological regions of the world in terms of case incidence and mortality. This study is also an endeavor to review and analyze the gradual changes of the genetic makeup of SARS CoV from evolutionary and epidemiological perspectives
Swelling and rheological study of calcium phosphate filled bacterial cellulose-based hydrogel scaffold
No full textThis work focuses mainly about swelling and rheological properties of calcium phosphate filled bacterial cellulose (BC)-based hydrogel scaffolds. Calcium phosphate is incorporated in the form of hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) in different ratios, that is, 00:00, 10:90, 20:80, 40:60, 50:50, and 60:40. These scaffolds are also comprised with polyvinylpyrrolidone (PVP), poly(ethylene glycol), agar, and glycerin; designated as “BC-PVP” and “BC-PVP-β-TCP/HA.” All the hydrogel scaffolds are showing the notable viscoelastic property at 28 and 37 °C temperatures. The degree of swelling is found significant in BC-PVP-β-TCP/HA_50:50 scaffold and it is notably elastic at 37 °C after 5 min of swelling. However, after 60 min of swelling and at equilibrium swelling state, the elastic property of BC-PVP-β-TCP/HA_20:80 is revealed the highest. Considering the degree of swelling and rheological properties, the BC-PVP-β-TCP/HA_50:50 and BC-PVP-β-TCP/HA_20:80 hydrogel scaffolds found suitable for their application in bone tissue engineering or bone tissue regeneration. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48522. © 2019 Wiley Periodicals, Inc.Internal Grant Agency, Tomas Bata University in Zlin, Czech Republic [IGA/CPS/2018/008]; Ministry of Education, Youth, and Sports of The Czech Republic-NPU Program I [LO1504
Words in DNA sequences: some case studies based on their frequency statistics
No full textOne of the critical requirements of data analysis involving large DNA sequences is an effective statistical summarization of those sequences. In this article DNA sequences have been analyzed based on word frequencies. Our analysis focuses on the detection of structural signature of a genome reflected in word frequencies and identification of phylogenetic relationships among different species reflected in the variation of word distributions in their DNA sequences. We have carried out a statistical study of the complete genome of baker's yeast, of various ribosomal RNA sequences from different prokaryotic and eukaryotic organisms and of the full genomes of some bacteriophages. Our exploratory analysis amply demonstrates the usefulness of DNA word frequencies in reducing the dimensionality of large sequences while retaining some of the structural information there that can have biological significance. Some conceptual issues that arise in course of our investigation have been addressed. A few interesting problems related to the statistics of DNA words have been pointed out with some indication of their possible solutions. The work has been partially motivated by the fact that sequence alignment and homology techniques that are quite popular for comparing and analyzing relatively smaller DNA sequences of nearly equal sizes are not applicable to data consisting of large sequences with widely varying sizes, which may contain segments with unknown or no biological functions, and consequently their comparison through functional homology is either impossible or extremely difficult
Identification of polymorphic motifs using probabilistic search algorithms
No full textThe problem of identifying motifs comprising nucleotides at a set of polymorphic DNA sites, not necessarily contiguous, arises in many human genetic problems. However, when the sites are not contiguous, no efficient algorithm exists for polymorphic motif identification. A search based on complete enumeration is computationally inefficient. We have developed probabilistic search algorithms to discover motifs of known or unknown lengths. We have developed statistical tests of significance for assessing a motif discovery, and a statistical criterion for simultaneously estimating motif length and discovering it. We have tested these algorithms on various synthetic data sets and have shown that they are very efficient, in the sense that the "true" motifs can be detected in the vast majority of replications and in a small number of iterations. Additionally, we have applied them to some real data sets and have shown that they are able to identify known motifs. In certain applications, it is pertinent to find motifs that contain contrasting nucleotides at the sites included in the motif (e.g., motifs identified in case-control association studies). For this, we have suggested appropriate modifications. Using simulations, we have discovered that the success rate of identification of the correct motif is high in case-control studies except when relative risks are small. Our analyses of evolutionary data sets resulted in the identification of some motifs that appear to have important implications on human evolutionary inference. These algorithms can easily be implemented to discover motifs from multilocus genotype data by simple numerical recoding of genotypes
